宏的使用

1.数字的奇数位和偶数位交换

#include<stdio.h>
#include<stdlib.h>
#define EXCHANGE(x) \
     (((((x)&0x55555555))<<1) | ((((x)&0xaaaaaaaa)>>1)))
int main()
{
    int x = 123;
    printf("%u\n", EXCHANGE(x));
    system("pause");
    return 0;
}

2.实现两个数中求较大值

#include<stdio.h>
#include<stdlib.h>
#define MAX(a,b) ((a>b)?a:b)
int main()
{
    printf("%d\n",MAX(5,6));
    system("pause");
    return 0;
}